Nervous Zimbabweans are battening down the hatches, fearing heightened repression and civil unrest following presidential elections that begin tomorrow.

"I'm going fishing," said one man in Ruwa. He was packing his family into their car and heading north to Lake Kariba, on the border with Zambia. "If the worst comes to the worst, we can sail across to safety."

Fearful that greater instability will follow the tense run-up to the presidential elections, middle-class Zimbabweans, black and white, who can afford to, have hatched security plans for their families.

Anxiety is in the air, in the capital Harare and countrywide, about an election that opposition supporters hope will deliver urgently needed change to a country that was once Africa's democratic hope.

People are not necessarily expecting trouble during polling tomorrow and Sunday. Of more concern is what happens afterwards.

Some people are stocking up with provisions, so there will be less need to venture onto the streets. Others have sent their children to South Africa, or other parts of the region they believe to be safer. Others have made rapid exit plans.

A slim victory by President Mugabe, who has done everything in his power to win the vote, would radicalise opposition supporters and could be followed by a wave of civil unrest.

There are indications that a narrow victory by Mr Mugabe's opponent, Morgan Tsvangirai, would be not be accepted by the ruling party or the army, and that too could plunge the country into chaos.

Zimbabwe's 4,000 white commercial farmers, most of whose farms have been invaded by the land-hungry poor with the encouragement of the government, have worked out security tactics at district level, especially in Zanu-PF strongholds such as Mashonaland.

Ben Zietsman, of the Commercial Farmers Union in MDC-supporting Matabeleland, said: "Farmers are not anticipating problems but they're being cautious. They've been improving communication networks and making plans in case the situation gets out of hand. Farmers are staying home to look after their assets, but quite a few have sent their families into towns."

A farmer's wife said: "I'm voting and then heading for South Africa with our kids." Her husband added: "Nobody's getting in here without a fight. I'm armed and dangerous."

Often prefaced with "we're not expecting trouble but..." many people said they were increasing home security, checking locks and making plans to leave fast.

At the Italian Bakery in Harare's upmarket Avondale, a security man unzipped his bulky wallet to reveal a box of bullets. He said: "I'm probably being paranoid – I guess that's the nature of my business – but I stocked up with these today and I feel safer for it."

Zimbabwe's middle classes have resources and thus options. That is not the case for country's poor black majority.

An office cleaner who lives in Chitungwiza, said: "We're expecting trouble and we're scared, but we're definitely going to vote. There is no safety in our small homes in the high-density suburbs. All we can do is hope."